Method of and apparatus for crimping synthetic fibres



P 1969 HIDEYUKI TSUZIMOTO ETAL 3,469,293

METHOD OF AND APPARATUS FOR CRIMPING SYNTHETIC FIBRES Filed June 8, 1967 ZJYJ a M C w H B 6 7 a 7 i V L 0 l ,u 7 71 I2 2 United States Patent 3,469,293 METHOD OF AND APPARATUS FOR CRIMPING SYNTHETIC FIBRES Hideyuki Tsuzimoto, Toyonaka-shi, and Megumi Ikerla, Akashi-shi, Japan, assignors to Asahi Kasei. Kogyo Kabushiki Kaisha, Kita-ku, Osaka, Japan, a corporation of Japan Filed June 8, 1967, Ser. No. 644,697 Claims priority, application Japan, June 18, 1966,

Int. Cl. Din 3/30 US. Cl. 28-1 5 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a method of and an apparatus for crimping synthetic fibres and more particularly to a method of and an apparatus for crimping synthetic fibres, which are capable of producing a crimped yarn with highly uniform crimp by stutter box crimping of synthetic fibres at high operational efficiency.

With reference to stuffer box crimping, various proposals have been made heretofore relative to the method of imparting 'crimp and the method of controlling the crimping operation, and to the crimped fibre take-up and heat setting mechanisms, solely for the purpose of obtaining crimped yarns having a highly uniform crimp. Although these proposals have proved to be effective to some extent, the crimped yarns obtained by the stulfer box crimping method, at the present time, are generally said in the market of crimped yarns to be considerably inferior to those obtained by other methods, e.g. by a false twisting method, in respect of uniformity in crimp.

According to the conventional stuffer box crimping method crimping and heat setting of yarns are most simply effected by providing heating means in a stuffer box, whereby crimp formation and heat setting are carried out simultaneously. Such a method, however, is not satisfactory from the standpoint of uniformity in crimp of the finished crimped yarn.

More specifically, variation in heating temperature in the stuffer box not only results in variation in thermal effect on the fibre but also results in non-uniform crimping of the fibre in the stuffer box, because the Youngs modulus is varied by the varying temperature of the fibre. Furthermore, variation in heating temperature causes variation in the frictional resistance between the wall surface of the stuffer box and the fibre mass, which in turn will cause variation in the pressure or the buckling pressure imposed on the fibre mass in the stuffer box, thereby rendering the crimp of the product crimped yarn inconsistent per se. As a result, the crimped yarn product becomes non-uniform or irregular in its dyeability due to uneven heating and this, together with the irregular crimp, will further deteriorate the quality of the finished yarn. The present inventors have found that it is preferable to carry out the crimping and heat setting separately from each other and that an independent space from the stuffer box, must be provided for separate heat setting operation.

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On the other hand, when heat setting of a crimped yarn is effected in a stufiing chamber provided after the stuffer box, the frictional resistance between the travelling fibre mass and the Wall surface of the stuffing chamber becomes extremely large due to heat, with the result that the fibre mass in the stuffing chamber is subjected to an extremely large pressure. This pressure increases gradually and finally reaches a value greater than the value of the regulated pressure of the fibre mass in said stufifer box. Accordingly, the pressure of the fibre mass in the stutter box is also built up under the influence of said high pressure to a value at which it is no longer possible to regulate the pressure of the fibre mass by pressurizing means provided in said box. In an extreme case, it will be impossible even to stuff the fibre into the stuffer box by means of the nip rolls. Thus, it becomes necessary to control the pressure of the fibre mass in the stuffing chamber after the stuifer box.

It is very difiicult to directly measure the pressure of the fibre mass. However, the pressure may be known indirectly by determining the percentage of the volume of the fibre mass to the volume of the stufling chamber, that is, the stuffiness of the fibre mass in said stuffing chamber. Describing in further detail, increasing pressure of the fibre mass in the stuffer box signifies increasing compression of the fibre mass or increasing stuifiness. The pressure of the fibre mass in the stufier box or the stufiiness is regulated by the pressurizing means provided in said box. The compressed fibre mass discharged from the stuffer box into the stufling chamber is subjected to expansion or recompression depending upon the volume of said stufiing chamber, and is further compressed progressively as it proceeds through said chamber due to the frictional resistance between it and the wall surface of said chamber. The relationship between the stuffiness in the stuffer box and that in the succeeding stufling chamber appears to be of great significance in maintaining the fibre mass pressure of the stuffiness in the stutter box at a constant level.

The present inventors have conducted a study on the relationship mentioned above and found that the stuffiness of the fibre mass in the stutter box is not adversely influenced by the stuffiness in the stufiing chamber if the latter is not greater than of the former. It has also been revealed that too a small stuffiness in the succeding stufiing chamber brings about different problems. Namely, as is well known, when the pressure of the fibre mass having been stuffed in the stuffer box reaches a certain limit under the action of the pressurizing means, the fibre mass spouts out of the stuffer box upon opening of a pressure plate and thereby the pressure of the fibre mass in the stuffer box temporarily drops below said limit, so that spouting of the fibre mass from the stuffer box will not take place until the pressure thereof is built up again to said limit value. Such intermittent spouting of the fibre mass from the stuffer box causes the pressure of the fibre mass in the stuffer box to be varied periodically and obviously an irregular crimp results.

The present inventors have discovered that the aforementioned problem may be solved in the following manner. Namely, a stufiing chamber is provided after the stufiFer box and the pressure of the fibre mass having been discharged into the stufling chamber from the stuffer box is maintained at a value at least 40% of that in the stufier box. By so doing, it is possible to enable the fibre mass to be discharged from the stutter box continuously and smoothly and thereby to eliminate the pressure variation of the fibre mass in the stutter box.

As may be understood from the foregoing description, in order to maintain the fibre mass pressure in the stuffer box at a constant level or to maintain the crimping condition constant, it is necessary to provide the stuffing chamber after the stuffer box and also to control the stufiiness of the fibre mass in said stufiing chamber so as to fall within the range between 40 and 90% of that in the stuffer box. Under such condition, however, the stuffing chamber is subjected to so a large limitation in terms of its size, particularly its length, that it is no longer possible to carry out uniform heat setting of the crimp in said chamber.

In order to set the crimp in the yarn, it is desirable to erform heat setting of the fibre mass while maintaining said fibre mass in the folded and compressed state with a crimp therein to a possible extent in which it was in the stuifer box.

Heat setting effect on the folded portions of a crimp is greater when the crimp is heat set in a compressed state than when it is in a non-compressed state. For instance, the elongation of a crimp which is heat set in a relatively free, unconfined state after relaxing the compressed fibre mass is about one half of that of a crimp which is heat set in a compressed state, suggesting lessening of heat setting effect on the folded portions. In addition, for heating the massive fibre uniformly by means of a heating plate, a considerably long heating time is required as fibres generally have a low heat conductivity.

In this connection, the present inventors have found that, in order to obtain a finished yarn of high uniformity by the stutfer box crimping method, it is necessary to combine a stuffer box wherein crimp is imparted to the fibre, a take-up mechanism for taking up the fibre mass being discharged from said stutfer box and heat setting means under specific conditions.

According to the present invention, it is possible to obtain a highly uniform crimped yarn having a desired crimp under stable operating conditions by th combination, under specific conditions, of a crimping chamber, a take-up mechanism for taking up the fibre mass being discharged from said crimping chamber and a heat treatment mechanism for heat setting the crimp in the crimped yarn.

The object of the present invention, therefore, is to provide a method of and an apparatus for producing a highly uniform crimped yarn, in which the step of imparting a uniform crimp to the yarn in a stufier box and the step of heat setting the resultant crimp, which are the major steps in the stuffer box crimping, are combined successively with each other, and which are operable at high efiiciency as a whole.

According to the present invention, in forcibly introducing a fibre into a stuffer box by means of a pair of nip rolls provided adjacent said stuffer box to form a crimp in said fibre, the pressure of the fibre mass formed in said box is controlled by pressurizing means provided at a discharge opening of said box so as to produce a desired crimp in said fibre, and thereafter the fibre mass having been discharged from the stuffer box is transferred into a chute formed between the stutfer box and a rotary heat setting drum. The rotation of the rotary drum is adjusted so that the stufliness of the fibre mass in the chute is maintained within the range from 40 to 90% of that in the stutfer box, so that the fibre mass may be taken up positively on the rotary drum. The crimp in the crimped fibre mass is heat set with a heating medium which penetrates therethrough during travelling of said fibre mass towards an Outlet opening of the apparatus while being carried on the drum. The chute serves to effect smooth transfer of the fibre mass from the stufier box onto the rotary drum, to provide together with a heat setting space above the peripheral surface of the rotary drum a stuifing chamber in successive relation to the stuifer box, and to enable the fibre mass to be discharged from the stutfer box and transferred onto the rotary drum smoothly, thereby minimizing the pressure variation of the fibre mass in the stuffer box. Th stufiiness in the chute is adjusted by changing the take-up speed of the rotary drum and may also be adjusted by changing the interior volume of the chute by displacing a movable member which constitutes the bottom of the chute.

In the present invention, as described above, the pressure of the fibre mass in the stutfer box is controlled by the pressurizing means provided at the discharge opening of said box. It should, however, be noted that the pressure of the pressurizing means does not in any way represent the pressure of the fibre mass in the stuifer box, though it may be correlated to the latter. The pressure of the fibre mass in the stuffer box is variable depending upon the size of the stuffer box and the friction between th fibre mass and the inner wall of said stulfer box. Therefore, a pressure gauge for pressuring means in a specific apparatus is not commonly applicable to the pressurizing means in the inventive apparatus to measure the pressure of the fibre mass in the stuffer box.

In the present invention, therefore, the ratio of the volume of crimped fibre mass stuffed in the stutfng box and the chute to the interior Volumes of said stufier box and said chute, which is referred to as stufiiness by the present inventors, is obtained, for which the pressure of the pressure plate and the take-up speed of the rotary drum are determined experimentally.

The heating medium penetrates through the fibre mass on the rotary drum and flows from the outer peripheral surface towards the center of said rotary drum under suction, so that the fibre mass is held in tight contact with the surface of the drum and carried thereon towards the outlet opening as said drum rotates.

Heated air or superheated steam is conveniently used as the heating medium. The temperature of the heating medium is variable depending upon the nature of the fibre to be treated, but is preferably from to 180 C. for nylon, and polyester fiber and from 100 to C. for polypropylene fiber. While, in general, better heat setting effect may be obtained with an extended heating period in the temperature ranges set forth above, it is recommendable to determine practical heat seting conditions through experiments.

The drawings show an apparatus embodying the present invention, in which:

FIGURE 1 is a vertical cross sectional of the apparatus and FIGURE 2 is a transverse cross section of the apparatus shown in FIGURE 1.

In order that the advantageous features of the present invention may be more clearly understood, a detailed description will be given hereunder with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, reference numerals 1 and 1' designate a pair of nip rolls. Doctor blades 3 and 3' have respective ends thereof in intimate contact with the nip rolls 1 and 1' respectively and define a stutfer box A together with side plates 7 and 7'. A pressure plate 4 is pinned at a fulcrum 5 and is caused to undergo pivotal movement about said fulcrum under the pressure of an air cylinder 6, thereby imparting resistance to a fibre mass 2' being discharged from said box A. A space B constitutes a chute connecting the box A with a space C formed in a combination take-up and heat setting means consisting of a rotary drum to be described later. The chute is composed of an inner wall member which is curved somewhat on one side which is adjacent the space C, so as to ease introduction of the fibre mass into the space C. The space E is defined by the side plate 7 and 7 which also define the stuffer box A, an upper wall member 8 formed integrally with the upper doctor blade 3 and a lower movable member 8' pinned at a fulcrum 9. The position of the lower movable member 8' is adjustable by a bolt 10. The rotary drum 11, as shown in FIG. 2, has a number of small holes 20 in the peripheral surface thereof and is formed with flanges 11 composing a groove structure. An arcuate box structure 12 is arranged along the outer periphery of the rotary drum in contact therewith so as to cover part of said outer periphery. In the interior of the arcuate box structure is disposed a heating element 22 and the bottom wall 12 of said box structure confronting the perforated peripheral surface of the rotary drum is formed with a number of small holes 20. The perforated bottom wall 12' defines, together with the groove structure on the outer periphery of the rotary drum, the aforementioned heat setting space C into which the fibre mass is taken up. A heating medium is sucked in at the center of the rotary drum by means of a blower 13 and transferred through an outlet port 14 of said blower, a passage 15 and the space C to return to the center of said rotary drum. The rotary drum is said space B and wall surface defining said space is prevented from becoming excessively large. The degree of inclination of the slope is varied depending upon the denier of the yarn to be treated, a desired crimp and the rate of speed of crimping process, and should be determined experimentally.

The advantageous features of the present invention will be further described only by way of example hereunder. Using the apparatus shown in FIGS. 1 and 2, nylon fibres 210d/15f were crimped, the crimping conditions and the properties of the finished yarns being shown in table below.

TABLE Stnfliness in Drum speed! Pressure of Heat setting No. of enmp Crimp Crimp chute/stufiiness stufiing speed pressure late temperature (No/ mm.) Elongation elasticity in stufier box (ratio) (kg. cm!) 0.) (percent) (percent) (ratio) driven by suitable drive means (not shown) so as to ro- Remarks:

tate at a predetermined peripheral speed in a direction in which the fibre mass is to be carried. The rotary drum 11 is formed therein with a plurality of chambers 19 and each chamber has a through hole 16 formed in the boss section thereof. A hollow cylindrical bearing 18 which supports the rotary drum 11 is connected at one end to the inlet port of the blower 13, while the other end thereof is closed. The bearing is formed with a notch 17 through which the heating medium is sucked when notch 17 comes in register with the through hole 16 into the boss section of each chamber in the rotary drum. Thus, it will be understood that the heating medium in the respective chambers 19 is sucked successively in sequence as said rotary drum rotates. The transferring heating medium primarily consists of a mixture of air and steam which is injected through a steam inlet port 21, and is heated to a desired temperature by the heating element 22.

In operating the apparatus of the construction described above, a fibre is fed into the stufier box A with pressure by the nip rolls 1 and 1' against the pressure of the fibre mass 2 having previously been formed in-said box and is crimped therein. The pressure of the fibre mass is controlled by the pressure plate 4 which is operated under air pressure. The fibre mass which has been stuffed in the stuffer box A with crimp therein is forced forward under the pressure of the incoming fibre which is continuously fed in said box with pressure by the nip rolls 1 and 1', moved into the chute B and then introduced into the space C in the combination take-up and heat setting rotary drum. The rotary drum takes up the fibre mass in the shape in which it was discharged from the stuffer box, while rotating at such a peripheral speed as to maintain the stuffiness in the chute which is from 40 to 90% of that in the stuifer box. In the space C, the fibre mass is urged towards the peripheral surface of the rotary drum under the pressure of the heating medium being ejected into said space through the perforated bottom of the Wall structure and sucked through the perforations in the peripheral surface of the drum, and is carried thereon slowly towards the outlet opening at the other end of the space, while undergoing heat setting treatment. As the fibre mass comes to a point approximating the terminal end of the outer wall 12, where there is no ejection and suction of the heating medium taking place, it comes off the rotary drum to drop onto a chute 23 and is carried away on a suitable belt conveyor to be wound on suitable winding means. The position of the movable member 8' disposed in the space B connecting the crimping chamber A with the space C on the rotary drum is adjusted by the bolt 10 so as to adjust the inclination of the slope leading from the stufier box A to the space B, whereby the frictional resistance between the fibre mass travelling through (1) The crimp elongation and crimp elasticity were obtained from the following formulae in accordance with the Japanese Industrial Standards No. 1077.

Crimp elongation= X 100 wherein,

a stands for the length under initial load, that is the length of a 20 cm. sample as measured after leaving it under the initial load of gr. of the nominal denier for 1 minute,

stands for the length under load, that is the length of said sample as measured after elaving it under a load of gr. of the nominal denier for 30 seconds, and

0 stands for the length as measured after leaving the sample used for the measurement of b to stand for 2 minutes after removal of the load and then placing the same under the load of a for 30 seconds.

(2) The stufiiness is obtained by dividing the weight of the fibre in the chamber by the true specific gravity thereof and further by the volume of the chamber.

(3) The nip rolls were driven at the rate of 100 'm./ min.

As may be seen in the table above, Test Nos. 1, 3 and 4 were conducted under the same conditions except that the ratio of the rate of speed of the take-up drum to the rate of speed of the nip rolls was varied. Namely, in these tests, the ratio of the stufiiness in the chute to that in the stutter box was changed from 50 to With no significant change in the crimp of the finished yarns. Furthermore, it will be seen that the crimp elongation tends to increase as the speed ratio becomes smaller and therefore the ratio of the stufliness in the chute to that in the heat setting space becomes higher. This is attributed to the prolonged heat setting period and the difference in compressed state of the fibre mass during heat setting operation.

The results of Test Nos. 1 and 2 indicate that the number of crimps and elongation of the finished yarn varies largely with varying pressure of the fibre mass in the stufler box.

From the foregoing, it will be clear that a slight change in rate of speed of the take-up drum gives no substantial change to the crimp imparted to the fibre mass in the stutter box and that the crimping operation is controlled Ionly by the pressure of the pressure plate in the stutter During operation, as is obvious, no substantial change occurs in the crimp forming operation as both of the nip rolls and the take-up drum rotates nearly at a constant rate of speed, but even when a minor change occurs in the ratio between said rates of speed during an extended period of operation due to change in rate of speed of said rolls or drum, such change, according to the present invention, does not have any influence upon the crimp forming operation in the stutfer box, so that it is not necessary to maintain the speed ratio so precisely as would be required otherwise. The apparatus of this invention in which the crimp forming operation can be controlled merely by the simple pressure plate, is of high industrial advantage from the operational point of view.

The fabric knitted with the crimped yarn according to the present invention exhibited a high bulkiness and was of commercial value with no knitting line.

The method of the present invention may be used for stufiing either a single yarn or a plurality of yarns but most advantageously used for stuffing a plurality of yarns. The filament yarn to be used in the present invention may be of any type including filament yarn, multi-filament yarn, spun yarn or tow.

It should also be noted that the present invention is applicable to any kind of fibre and is most advantageously applied to the crimping of thermoplastic fibres. However, the application of the invention is not restricted only to those mentioned above but may be applied to the crimping, for example, of cellulose fibre, in combination with the resin curing method.

We claim:

1. A stuffer box crimping method comprising stuffing a fiber into a stuffer box, imparting a desired crimp to the fiber mass in said stuffer box while adjusting the pressure exerted on said fiber mass, transferring the fiber mass from the stuffer box into a chute formed between the stuffer box and a rotating drum, positively taking up the fiber mass on the rotating drum, rotating the drum at a rate of speed so adjusted that the degree of stuffiness in the chute is maintained at 40 to 90% of that in the stuffer box, and heat setting said fiber mass on said rotary drum by passing a heating medium through said fiber mass.

2. A method according to claim 1 in which the synthetic fibre is nylon, a polyester fibre or a polypropylene fibre.

3. A method according to claim 1 in which the fibre is the form of a yarn filament, a multi-filament yarn or a tow.

4. A method according to claim 1 in which the temperature of the heating medium is from to 180 C. for nylon, and polyester fibre and from 100 to C. for polypropylene.

5. Apparatus for crimping synthetic fibres, comprising a stuffer box including a pressure plate provided at a discharge opening thereof for adjusting the pressure of a fibre mass being formed therein, a chute structure, and heat-treating and take-up means constituted by a rotary setting drum having a perforated groove structure along the outer periphery thereof, means for driving said drum at an optional speed and arcuate perforated fixed wall structure along the outer periphery of said drum in contact therewith, said rotary drum and said wall structure mutually defining a heat-treatment space therebetween, and means for transferring a heating medium through the perforated fixed wall structure and the perforated groove structure at the outer periphery of the rotary drum across said heat-treatment space.

References Cited UNITED STATES PATENTS 3,044,145 7/1962 Tager et a1 2872 X 3,146,512 9/1964 Heijnis 28-72 X 3,302,264 2/1967 Mattingly 2872 3,311,961 4/1967 Iwnicki et al 28- 72 DORSEY NEWTON, Primary Examiner US. Cl. X.R. 

